1. Field of the Invention
The present invention generally relates to a material handling system, and more particularly, to a controlled system for moving materials to various locations within a manufacturing facility.
2. Description of the Related Art
To remain competitive in the manufacturing industry, manufacturers are constantly seeking out new ways to increase productivity. Advances in technology have helped to increase productivity by providing numerically controlled devices, which allow for the introduction of automated manufacturing equipment. One of the most significant advances in technology for increasing productivity has been the introduction of computers to the manufacturing floor. Computers have made it possible to accurately monitor and track production systems so manufacturers can adapt more quickly to production demands. Computers also facilitate the use of robots. Robots allow for the real-time adaptation of the manufacturing environment to the demands of the production process. Generally, robots are used to transport materials around a factory floor to deliver items to, and remove items from, various process tools.
Robots require some way to present parts or material to and from the various types of processing equipment which they service. For example, one of the most common material transport systems, is an overhead lift system. In this example, the overhead lift system uses a platform suspended by suspension mechanisms, such as ropes, cables, wires, chains, belts, and the like, which are reeled up or down to raise or lower the platform. Unfortunately, in this system the ability to pick or place material at a given point is greatly limited due to lack of positional control of the material when the system lowers it due to side swaying and/or twisting. Also, the suspended transport system typically requires that the suspension mechanisms be reeled up and/or down, in unison, at the same rate, to prevent tilting of the carrier platform. This Requirement usually only met using carefully designed spooling mechanisms or other complex components. Further, most suspended transport systems fail to provide off-axis loading, which limits their usefulness.
An inline tool system for the automatic processing and/or automatic treatment of materials is yet another example of a common type of material transport system. FIGS. 1A and 1B are illustrations of a perspective and side view, respectively, of the inline system, which may include front-of-line (FOL) and/or back-of-line (BOL) tools. The FOL and BOL tools are used to treat and/or process semiconductor chips. The chips are typically contained in magazines M when they are transported. The magazines M are fed to the tools and prepared therein for processing or treatment and also for transporting away after the processing or treatment.
Arranged behind the line of tools, is a rail device T, on which runs a robot R, which grips, moves, positions and releases the magazines M as required. As shown in FIG. 1B, the mounting robot R travels rectilinearly and horizontally on the rail device T. A gripper G for the magazine M is supported movably on the mounting robot R by means of an advancing carriage V and a lifting carriage H. The advancing carriage V is movable on the mounting robot R horizontally and orthogonally to the rail device T towards one of the tools and away from it. The lifting carriage H is movable vertically on the advancing carriage V. Consequently, the gripper G can be moved with three Cartesian degrees of freedom or directions of movement with respect to the tools in order to bring the magazine M to the intended magazine position at the tool and unload it there, or to grip it there and lead it away.
The drawbacks to the above-described system are many. Foremost, as illustrated in FIG. 1B, rail device T of the inline system can require two feet or more of floor space, which can present a total space penalty of up to 30% on most factory floors. If the floor space includes clean room floor space, the cost associated with such a floor space penalty can be dramatically increased. Moreover, the inline system is not flexible in routing so that service can only be provided along a straight path.
The modern factory uses many different types of processing tools and equipment, some of which can be older existing equipment (i.e., legacy equipment), which may not be designed for the inline system of loading (e.g., rear loading). Instead, most legacy equipment is designed for front loading, typically via a loading chute. Thus, another drawback of most typical transport systems is that they are designed for rear loading and are thus not capable of chute loading. Most transport systems are also typically not flexible enough to support cell-to-cell transport or functional layout. Consequently, to implement a modern transport system in an existing factory may require the buying of new equipment and/or the making of expensive factory and equipment modifications.
For the above reasons, what is needed is a material transport system which can transport materials from one processing station or tool to another, in a rigid and controlled manner, while having flexibility in routing, and compactability for efficient space utilization.